Assembly for retaining a gear train in a turbomachine

Abstract

The invention relates to an assembly for holding an epicyclic gear train in a turbomachine comprising an annular housing in which are engaged a first annular part and a second annular part which are locked against rotation in the housing by first annular interlocking means and second annular interlocking means, respectively, wherein the first annular interlocking means are configured to allow a first circumferential clearance between the first annular part and the housing, the second annular interlocking means are configured to allow a second circumferential clearance between the second annular part and the housing, and the first circumferential clearance is strictly less than the second circumferential clearance.

The invention claimed is: 
     
       1. An assembly for holding an epicyclic gear train in a turbomachine, the assembly comprising an annular housing in which are engaged a first annular part and a second annular part which are locked against rotation in the annular housing by first annular interlocking means and second annular interlocking means, respectively, wherein:
 the first annular interlocking means are configured to allow a first circumferential clearance between the first annular part and the annular housing; 
 the second annular interlocking means are configured to allow a second circumferential clearance between the second annular part and the annular housing; and 
 the first circumferential clearance is strictly less than the second circumferential clearance. 
 
     
     
       2. The assembly according to  claim 1 , wherein the first annular part has an axial rigidity lower than an axial rigidity of the second annular part. 
     
     
       3. The assembly according to  claim 1 , wherein the first annular part has a circumferential rigidity lower than a circumferential rigidity of the second annular part. 
     
     
       4. The assembly according to  claim 1 , wherein the first annular part has an axial rigidity and a circumferential rigidity lower, respectively, than an axial rigidity and a circumferential rigidity of the second annular part. 
     
     
       5. The assembly according to  claim 1 , wherein the first annular part comprises at least one annular bulge formed axially between the first annular interlocking means and an opposing annular flange for attachment to an outer sun gear of an epicyclic gear train. 
     
     
       6. The assembly according to  claim 1 , wherein the first annular part and the second annular part are fixed to each other by annular flanges. 
     
     
       7. The assembly according to  claim 6 , wherein the annular flanges are axially opposite to the first annular interlocking means and the second annular interlocking means. 
     
     
       8. The assembly according to  claim 1 , wherein the first circumferential clearance is between 0 and 0.2 mm. 
     
     
       9. The assembly according to  claim 8 , wherein the second clearance is between 0.5 and 2 mm. 
     
     
       10. The assembly according to  claim 1 , wherein the first annular interlocking means comprises:
 a first plurality of series of axial ribs, each of the first series being circumferentially spaced and formed on one of the first annular part and the annular housing. 
 
     
     
       11. The assembly according to  claim 10 , wherein each of the first series is circumferentially spaced and formed on the first annular part. 
     
     
       12. The assembly according to  claim 10 , wherein each of the first series is circumferentially spaced and formed on the annular housing. 
     
     
       13. The assembly according to  claim 10 , wherein the first annular interlocking means comprises:
 a second plurality of series of axial ribs, each of the second series being circumferentially spaced and formed on one of the first annular part and the annular housing. 
 
     
     
       14. The assembly according to  claim 1 , wherein the second annular part is radially interposed between the first annular part and an annular shell of the annular housing. 
     
     
       15. The assembly according to  claim 1 , further comprising a third annular part interposed annularly between the second annular part and the annular housing. 
     
     
       16. The assembly according to  claim 15 , wherein the third annular part comprises axial arms fixed by bolting to the first annular part. 
     
     
       17. A housing assembly comprising the assembly for holding an epicyclic gear train in a turbomachine according to  claim 1 , further comprising an epicyclic gear train comprising an outer sun gear and planet gears, the planet gears meshing with the outer sun gear. 
     
     
       18. The housing assembly according to  claim 17 , wherein the epicyclic gear train further comprises an inner sun gear, the planet gears meshing with the inner sun gear. 
     
     
       19. The housing assembly according to  claim 18 , wherein the inner sun gear, the outer sun gear, and the planet gears are each rotatably mounted on a planet carrier. 
     
     
       20. A gas turbomachine for aircraft comprising the housing assembly according to  claim 19 , wherein a central pinion of the epicyclic gear train is rotationally integral with a shaft of a compressor of the gas turbomachine.